In recent years noncontact type individual identification systems that employee RFID (Radio Frequency Identification) tags have been focused on for use in systems for managing the entire lifecycle of a product, including all commercial aspects of manufacturing a product, its distribution and sales. Radio wave type RFID tags that use 2.45 GHz microwaves are noted for the structure that includes an external antenna attached to an IC chip which enables communication to be performed over several meters. Presently, construction is ongoing of systems that operate for distribution of mass-manufactured products as well as their product management and product history management.
Current examples of radio wave type RFID tag systems using microwaves include products developed by Hitachi or Renesas that use a TCP (Tape Carrier Package) inlet. The manufacture of the TCP type inlet employs the TAB (Tape Automated Bonding) method in which IC chips having all external electrodes formed on the same surface thereof are mounted, each individually, on a tape carrier formed of a polyimide substrate with a succession of copper antenna circuits (Kouyama Susumu and Naruse Kunihiko “VLSI Packaging Technology”, first and second volumes, Nikkei BP, 1993). RFID tag manufacturing processes employing a typical TAB method will now be described with reference to FIG. 1.
As shown in FIG. 1 (a) of FIG. 1, after an IC chip 110 having a gold bump 104 formed on the circuit surface and in which all external electrodes are formed on the same face is separated into individual pieces by a dicing process, the individual piece is sucked from a dicing film 10 using a vacuum suction unit 20. Next, as shown in FIG. 1 (b), the piece is moved to a vacuum suction station 30 so that the gold bumps 104 of the IC chip 110 having all external electrodes formed on the same face thereof are on upper face. Next, as shown in FIG. 1 (c) the vacuum suction station 30 is inverted such that the gold bumps 104 become the lower face. Next, the IC chip 110 having all of the external electrodes thereof formed on the same face is positioned in the determined position with respect to an antenna substrate 500, being a polyimide substrate with copper film attached produced such that the copper film of that substrate is formed as an antenna circuit, and thereafter the IC chip 110 is secured in place by a thermal compression binding process using a heater 40. Connections can then be formed at the connecting parts of the gold bumps on the antenna circuit 501 by a tin-gold alloy formed by applying a tin or solder plating thereto. As shown in FIG. 1 (d), the gaps occurring between the IC chip 110 having all external electrodes formed on the same face thereof and the substrate 500 are sealed using a thermoset resin 600. The condition of this thermoset resin once the thermosetting process is complete is the intermediate condition of the RFID tag called an inlet. Accommodating this inlet in a label or thin case enables it to be used as an RFID tag.
Other inlet structures include for example having an IC chip in which the external electrodes of the IC chip are formed individually on the respective surfaces of a pair of opposing surfaces, as developed by Usami of Hitachi, having a glass diode package structure in which a dipole antenna connects to each external electrode formed on the respective surfaces (Japanese Unexamined Patent Application Publication No. 2002-269520). Further, in the device disclosed by Usami et al. when the IC chip in which the above described two external electrodes are formed individually on each of the surfaces of a pair of opposing surfaces of the IC chip is furnished with an excitation slit type dipole antenna, the external electrodes formed individually on each of the surfaces of a pair of opposing surfaces of an IC chip are disposed between the legs of an antenna to produce a sandwich antenna construction (ISSCC Digest of Technical Papers pages 398-399, 2003). In this dipole antenna structure having an excitation slit, the impedance of the antenna and input impedance of the IC chip can be made compatible by changing the width and length of the slit, thereby increasing the distance of achievable transmission.